1. Field of the Invention
The present invention relates to a method and system for protecting a broadcast frame. More particularly, the present invention relates to a method for protecting a frame broadcasted through a packet switching network by authenticating a frame based on a timed efficient stream loss-tolerant authentication (TESLA) scheme.
2. Description of the Related Art
According to the IEEE 802.11i standard, which is incorporated herein by reference, a security mechanism for protecting a data frame has been proposed, but no protection of a management frame has been considered. A TESLA scheme could be used for a broadcast frame authentication. In a TESLA scheme, a sender generates the key chain {K0, . . . , Kn}, where    Ki=Hi(RAND)=(H( . . . H(RAND))),    for example, K0=H(K1)=H(H(K2)) and H(*), a one-way hash function, and publishes the verification key K0. The broadcast message M, sent in the period j, is protected using key Kj in the following way: M→j∥Kj−1∥M∥MIC(Kj,j∥Kj−1∥M), wherein MIC represents the message integrity code.    Message M may be verified only after the reception of any message M′ sent in the period j+1, which includes key Kj. After reception of message M′ a receiver verifies key Kj using K0=Hj(Kj) or Kj−1=H(Kj) and verifies MIC in message M using key Kj. Accordingly, when the verification of the MIC and the verification of the key are all successful, the message is authenticated and considered trustworthy.
According to the TESLA scheme, the receiver cannot instantly perform the authentication at a point in time in which the broadcast frame is received from the sender. Instead, the receiver performs the authentication only after the frame from next interval is received. Accordingly, the TESLA scheme suffers from certain drawbacks such as delayed authentication due to the time difference between the data reception and the authentication.
Accordingly, there is a need for an improved system and method for protecting a frame broadcasted through a packet switching network by authenticating a frame based on a TESLA scheme.